1. Field
The present disclosure relates to a drug delivery system comprising a layered structure.
2. Description of the Related Art
In order for a drug to act effectively in a living area, the drug must be able to be expressed in the intended target area, and the in vivo concentration of the drug in the target area should be maintained in the therapeutic range for a certain period of time or longer. If a drug is present in an excessive amount in the body, it will show toxicity, and if the drug is present in an exceedingly small amount, it will show no therapeutic effect. A drug delivery system can function to control the amount of a drug in the body.